1. Field of the Invention
The present invention relates to a solid electrolytic capacitor and a method of manufacturing the solid electrolytic capacitor, and particularly to a solid electrolytic capacitor with suppressed occurrence of short circuit and a method of manufacturing the solid electrolytic capacitor.
2. Description of the Related Art
Recently, electronic devices have been downsized and increased in frequency, which also requires downsizing and increased frequency of a capacitor that is an electronic component of an electronic device. An example of capacitors suitable for being downsized is a solid electrolytic capacitor including an anode body of a valve metal, a dielectric film formed on the anode body, and a layer of manganese dioxide or a conductive polymer for example formed on the dielectric film.
In the solid electrolytic capacitor, the dielectric film is produced through a chemical conversion performed on the valve metal of which the anode body is formed. The dielectric film produced in the above-described manner is extremely dense, highly durable, and very thin. The solid electrolytic capacitor can therefore be downsized without being reduced in capacitance, as compared with other types of capacitors such as paper capacitor and film capacitor.
Although such a solid electrolytic capacitor can be downsized, the downsized capacitor tends to encounter increased occurrences of leakage current (LC) and short circuit in the manufacturing process. Even after the capacitor has been manufactured, a high-temperature reflow process tends to cause LC.
With the purpose of suppressing such occurrence of short circuit, Japanese Patent Laying-Open No. 2005-109252 for example discloses the following method. An anode body on which a dielectric film is formed is immersed in a polymerizable monomer solution and dried so that a conductive polymer layer is formed, and thereafter further immersed in a conductive polymer solution (or conductive polymer solution is applied) and dried. According to Japanese Patent Laying-Open No. 2005-109252, this method can uniformly form the conductive polymer layer and thereby suppress occurrence of short circuit.
Currently, however, the need to suppress occurrence of short circuit still remains. Further, in addition to and simultaneously with suppression of occurrence of short circuit, maintenance of capacitor's intrinsic characteristics such as maintenance of the capacitance and suppression of increase in ESR (Equivalent Series Resistance), for example, are required.